U.S. patent number 10,919,539 [Application Number 16/307,308] was granted by the patent office on 2021-02-16 for method for operating a vehicle control system.
This patent grant is currently assigned to Robert Bosch GmbH. The grantee listed for this patent is Robert Bosch GmbH. Invention is credited to Charlotte Grinenval, Konrad Hofmann, Stefan Wickert.
United States Patent |
10,919,539 |
Hofmann , et al. |
February 16, 2021 |
Method for operating a vehicle control system
Abstract
In a method for operating a vehicle control system having at
least two actuators acting upon a vehicle state variable, a first
actuator is initially activated, and at a time interval prior to
arrival at a boundary condition regarding the first actuator, a
switchover is made to a second actuator.
Inventors: |
Hofmann; Konrad (Ilsfeld,
DE), Grinenval; Charlotte (Markgroeningen,
DE), Wickert; Stefan (Albershausen, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Robert Bosch GmbH |
Stuttgart |
N/A |
DE |
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Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
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Family
ID: |
1000005363924 |
Appl.
No.: |
16/307,308 |
Filed: |
April 7, 2017 |
PCT
Filed: |
April 07, 2017 |
PCT No.: |
PCT/EP2017/058401 |
371(c)(1),(2),(4) Date: |
December 05, 2018 |
PCT
Pub. No.: |
WO2017/215808 |
PCT
Pub. Date: |
December 21, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190135301 A1 |
May 9, 2019 |
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Foreign Application Priority Data
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Jun 13, 2016 [DE] |
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102016210382.2 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W
50/029 (20130101); B60K 28/10 (20130101); B60T
2270/413 (20130101); B60W 2050/0292 (20130101); B60T
2270/402 (20130101) |
Current International
Class: |
B60W
50/029 (20120101); B60K 28/10 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1026060 |
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Aug 2000 |
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EP |
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3000673 |
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Mar 2016 |
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EP |
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3000673 |
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Mar 2016 |
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EP |
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2015008590 |
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Jan 2015 |
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WO |
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Other References
International Search Report for PCT/EP2017/058401, dated Jul. 12,
2017. cited by applicant.
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Primary Examiner: Antonucci; Anne Marie
Assistant Examiner: Cromer; Andrew J
Attorney, Agent or Firm: Norton Rose Fulbright Us LLP
Messina; Gerard
Claims
What is claimed is:
1. A method for operating a vehicle control system including at
least two actuators acting upon a driving state variable, the
method comprising: initially activating, to influence the driving
state variable, a first actuator of the at least two actuators; and
performing, via an actuating signal of a regulating and control
unit, a switchover to a second actuator of the at least two
actuators at a time interval prior to arrival at a limiting
boundary condition of the first actuator, wherein the limiting
boundary condition differs from the driving state variable that is
controllable via activation of the actuator; wherein in an initial
state, a selected distribution is carried out between the at least
two actuators, wherein the vehicle is a hybrid vehicle having an
electric drive motor and an internal combustion engine and a
hydraulic braking system, in which at least one of the at least two
actuators is associated with the electric drive motor and another
of the at least two actuators is associated with the internal
combustion engine and a hydraulic braking system, wherein a
weighting of the actuators, which act together upon a same driving
state variable, is adjustable, so that a contribution of each
actuator is settable variably for attaining the driving state
variable, wherein a time of arrival at the limiting boundary
condition is determined from a characteristic curve of the driving
state variable, and wherein boundary conditions are taken into
account in the electric drive motor and in the hydraulic braking
system, in response to exceedance of limiting values, wherein the
boundary conditions for the electric drive motor and the hydraulic
braking system result in functional impairment of the actuators,
and wherein a voltage state of a vehicle battery, which is charged
in a generator mode of the electric drive motor is monitored,
wherein the generator mode is sustained until the vehicle battery
is charged, wherein a current state of the charge in the vehicle
battery is monitored; temporally prior to arrival at a maximum
state of charge, which represents a limiting value, a switchover
being made to the vehicle brake as the solely active actuator
during the braking.
2. The method as recited in claim 1, wherein the time interval
prior to the switchover between the at least two actuators is such
that the switchover is concluded prior to arrival at the boundary
condition of the first actuator.
3. The method as recited in claim 1, wherein the switchover between
the at least two actuators is carried out in a continuous and
overlapping manner.
4. The method as recited in claim 1, wherein in an initial state,
only a subset of the at least two actuators is active, the method
further comprising: at the switchover, deactivating actuators of
the subset, and activating an actuator that is not part of the
subset.
5. The method as recited in claim 1, wherein in an initial state,
at least two actuators of the at least two actuators are active
simultaneously, the method further comprising: at the switchover,
changing the weighting between the at least two actuators.
6. The method as recited in claim 1, wherein the method is used
during braking of a vehicle.
7. The method as recited in claim 6, wherein at least one of the at
least two actuators is used for generating a braking force and
includes an electric drive motor in a vehicle, in a generator
mode.
8. The method as recited in claim 6, wherein at least one of the at
least two actuators is used for generating a braking force and
includes a hydraulic pump in a hydraulic vehicle brake.
9. The method as recited in claim 6, wherein at least one of the at
least two actuators includes an internal combustion engine in an
overrun mode used for generating a drag torque.
10. The method as recited in claim 1, wherein the method is used
during steering of a vehicle.
11. The method as recited in claim 10, wherein at least one of the
at least two actuators includes an electric servomotor in a
steering system of a vehicle that is used for generating a steering
torque.
12. A vehicle control apparatus, comprising: a vehicle control
system, including at least two actuators acting upon a driving
state variable; wherein the vehicle control system is configured to
perform the following: initially activating, to influence the
driving state variable, a first actuator of the at least two
actuators, and performing a switchover to a second actuator of the
at least two actuators at a time interval prior to arrival at a
limiting boundary condition of the first actuator, wherein the
limiting boundary condition differs from the driving state variable
that is controllable via activation of the actuator; wherein
between the actuators, the switchover is made via an actuating
signal of a regulating and control unit, wherein in an initial
state, a selected distribution is carried out between the at least
two actuators, wherein the vehicle is a hybrid vehicle having an
electric drive motor and an internal combustion engine, in which at
least one of the at least two actuators is associated with the
electric drive motor and another of the at least two actuators is
associated with the internal combustion engine and a hydraulic
braking system, wherein a weighting of the actuators, which act
together upon the same driving state variable, is adjustable, so
that a contribution of each actuator is settable variably for
attaining the driving state variable, and wherein a time of arrival
at the limiting boundary condition is determined from a
characteristic curve of the driving state variable, and wherein
boundary conditions are taken into account in the electric drive
motor and in the hydraulic braking system, in response to
exceedance of limiting values, wherein the boundary conditions for
the electric drive motor and the hydraulic braking system result in
functional impairment of the actuators, and wherein a voltage state
of a vehicle battery, which is charged in a generator mode of the
electric drive motor is monitored, wherein the generator mode is
sustained until the vehicle battery is charged, wherein a current
state of the charge in the vehicle battery is monitored; temporally
prior to arrival at a maximum state of charge, which represents a
limiting value, a switchover being made to the vehicle brake as the
solely active actuator during the braking.
13. An apparatus for controlling adjustable components of a vehicle
control system, comprising: a regulating and control unit for
operating a vehicle control system, which includes at least two
actuators acting upon a driving state variable, wherein the vehicle
control system is configured to perform the following: initially
activating, to influence the driving state variable, a first
actuator of the at least two actuators, and performing a switchover
to a second actuator of the at least two actuators at a time
interval prior to arrival at a limiting boundary condition of the
first actuator, wherein the limiting boundary condition differs
from the driving state variable that is controllable via activation
of the actuator; wherein the vehicle control system includes at
least two actuators that act upon the driving state variable, and
wherein between the actuators, the switchover is made via an
actuating signal of the regulating and control unit, wherein in an
initial state, a selected distribution is carried out between the
at least two actuators, wherein the vehicle is a hybrid vehicle
having an electric drive motor and an internal combustion engine,
in which at least one of the at least two actuators is associated
with the electric drive motor and another of the at least two
actuators is associated with the internal combustion engine and a
hydraulic braking system, and wherein a weighting of the actuators,
which act together upon a same driving state variable, is
adjustable, so that a contribution of each actuator is settable
variably for attaining the driving state variable, and wherein a
time of arrival at the limiting boundary condition is determined
from a characteristic curve of the driving state variable, and
wherein boundary conditions are taken into account in the electric
drive motor and in the hydraulic braking system, in response to
exceedance of limiting values, wherein the boundary conditions for
the electric drive motor and the hydraulic braking system result in
functional impairment of the actuators, and wherein a voltage state
of a vehicle battery, which is charged in a generator mode of the
electric drive motor is monitored, wherein the generator mode is
sustained until the vehicle battery is charged, wherein a current
state of the charge in the vehicle battery is monitored; temporally
prior to arrival at a maximum state of charge, which represents a
limiting value, a switchover being made to the vehicle brake as the
solely active actuator during the braking.
Description
FIELD OF THE INVENTION
The present invention relates to a method for operating a vehicle
control system in a vehicle having at least two actuators, which
act upon the same driving state variable.
BACKGROUND INFORMATION
Vehicle control systems are known, which control the interaction of
different actuators in the vehicle that influence the same driving
state variable. For example, hybrid vehicles having an electric
drive motor and an internal combustion engine are known; either
only the electric drive motor, the drive motor together with the
internal combustion engine, or only the internal combustion engine
being active as a function of different parameters and state
variables. In such hybrid vehicles, it is also known that during
braking operation, the electric drive motor may be used as a
generator in regeneration mode, in order to recharge the vehicle
battery. The regeneration is carried out in response to a braking
request by the driver; the hydraulic vehicle brake being able to be
additionally activated, in order to attain a requested setpoint
deceleration. As soon as the vehicle battery has attained a certain
state of charge, a switchover is made to the hydraulic vehicle
brake as the only braking device.
SUMMARY
The method of the present invention relates to operation of a
vehicle control system including at least two actuators acting upon
a common driving state variable or vehicle state variable. The
actuators may be operated alternately, the operation being focused
on limiting boundary conditions. In some instances, the different
actuators may also be operated simultaneously; the weighting of the
actuators, which act together upon the same driving state variable,
being preferably adjustable, which means that the contribution of
each actuator may be set variably for attaining the driving state
variable.
At least one actuator is subject to a limiting boundary condition,
which differs from the driving state variable that is controllable
via activation of the actuator. The boundary condition limits, for
example, the operability of the actuator, the full operability
being ensured, as long as the boundary condition has not yet been
reached. However, upon reaching the boundary condition, the
operability of the actuator in question is not ensured or at least
no longer completely ensured.
In the method of the present invention, the time of arrival at the
limiting boundary condition is ascertained, in particular, from a
state variable or parameter of the actuator or of a unit assigned
to the actuator. This state variable or parameter, which is
ascertained, e.g., sensorially or on the basis of a mathematical
model, is monitored; the time of arrival at the limiting boundary
condition being able to be deduced from the characteristic curve of
the state variable or parameter.
A time span is calculated back from the time of arrival at the
limiting boundary condition, the time span accordingly being
situated at a time interval prior to the reaching of the boundary
condition. At this time, a switchover is made from the first
actuator to the second actuator. Therefore, the switchover is not
made only upon arrival at the limiting boundary condition, but
already at an earlier time, at which the operability of the first
actuator is still ensured without limitation. An advantage of this
procedure is that the transition from the first to the second
actuator may be carried out without limitations, which means that,
for example, with regard to ergonomic aspects, the transition may
take place with as little effect as possible on the driving feel.
Ideally, the switchover from the first to the second actuator is
implemented in such a manner, that it is not noticed by the driver.
Accordingly, the transition may be carried out under an additional
condition, for example, at a constant driving state variable, which
is influenced by the actuators, for example, at a constant vehicle
speed or constant vehicle deceleration or acceleration. Thus, the
transition between the actuators may be carried out smoothly and
without being perceived by the driver.
With the aid of the method, control systems in vehicles may be
operated, in which two or possibly more than two actuators act upon
the same driving state variable. The actuators may belong to either
the same module, for example, a brake system, or different modules,
for example, the brake system and the drive system, as long as the
present invention ensures that the actuators act upon the same
driving state variable of the vehicle.
The driving state variable is, for example, a kinematic driving
state variable, such as the vehicle speed or a vehicle acceleration
in the longitudinal, transverse and/or vertical direction. The
vehicle state variable also includes state variables, which
influence the driving state of the vehicle indirectly, for example,
the steering angle, the steering torque or the braking torque.
According to one advantageous variant, the time interval prior to
the switchover between the actuators is designed in such a manner,
that the switchover operation is concluded prior to arrival at the
limiting boundary condition of the first actuator. In this manner,
it is ensured that the full operability of each actuator also
remains ensured during the switchover operation between the
actuators. The first actuator would first arrive at its boundary
condition limiting the operability, after conclusion of the
switchover operation; however, at this time, the switchover
operation has already ended, and the driving state variable is
influenced by the further actuator(s).
According to another further, advantageous variant, the switchover
operation between the actuators takes place continuously and in an
overlapping manner. Accordingly, the switchover operation is not
carried out abruptly, but on the contrary, the activity of the
first actuator is continuously cut back, and at the same time, the
activity of the second actuator is increased. In the overlap phase,
the influence of the actuators on the vehicle state variable adds
up; the two actuators remaining below their maximum working
capacity, and in total, the influence on the vehicle state variable
remains constant; for example, a constant braking torque is
generated, which is on the same level as prior to the switchover
operation. For example, the switchover operation is carried out in
such a manner, that the vehicle state variable assumes the same,
constant value prior to, during and after the switchover
operation.
According to another further advantageous variant, in the initial
state, prior to the execution of the switchover operation, only a
subset of the actuators is active, which are deactivated after the
conclusion of the switchover operation; one or more further
actuators being active after the switchover operation.
Consequently, it is a complete change of activity from one actuator
to another actuator.
However, in one alternative variant, it is provided that both prior
to the switchover operation and after the switchover operation, at
least two actuators be active simultaneously, but that with the
switchover, the weighting between the actuators be changed. An
advantage of this variant is that the maintenance of the driving
state variable is distributed over different actuators, only the
state of activity between the actuators being changed at the
switchover. During braking operation of a hybrid vehicle, it is
possible, for example, prior to the switchover operation, to
generate the greater portion of the requested braking power, using
the electric drive motor in generator mode, and to generate the
lesser portion, using the hydraulic vehicle brake, in order to
carry out the regeneration; the conditions being reversed after the
switchover operation.
According to one more further, advantageous variant, a plurality of
actuators are active prior to the switchover operation and are
relieved by one or more actuators after the switchover operation;
in some instances, a modified weighting distribution also being
considered.
According to a further advantageous variant, the method of the
present invention is used during braking of the vehicle, in that
different actuators influencing the braking action are controlled.
In the hydraulic vehicle brake, a hydraulic pump, for example, an
ESP (electronic stability program) pump is used, for example, as an
actuator for generating braking force. The hydraulic pump may be
controlled in different ways before, during and after the
switchover operation.
An internal combustion engine in the vehicle, which generates drag
torques in overrun mode, may also be used as a further actuator,
which has an influence on the braking action of the vehicle and is
able to generate a braking force. The internal combustion engine in
overrun mode, the hydraulic vehicle brake and/or an electric drive
motor in generator mode may each be used as an actuator, which
generates braking force and has influence on the vehicle speed as a
driving state variable; a switchover between these actuators being
possible.
In order to prevent an excessively high brake temperature in the
hydraulic vehicle brake, it may be useful, for example, at a time
interval prior to reaching a critical brake temperature, to switch
over from a mode including actuation of the hydraulic vehicle
brake, to a mode including the internal combustion engine in
overrun mode. In this context, the switchover operation is
advantageously carried out continuously and in an overlapping
manner, in order to prevent brake jerk during the switchover.
According to a further advantageous variant, the method is used for
steering the vehicle; an electric servomotor for generating a
steering torque being used as an actuator in the steering system.
If the steering system is subjected to high mechanical loads, for
example, due to repeated or long-lasting activation of the steering
while the vehicle is stationary, or during off-road operation on
pathless terrain, then, for example, the temperature in the
electric servomotor may increase. Before this reaches a limiting
temperature value, an additional actuator influencing the steering
may be activated at a time interval prior to this. For example, the
steering system may be assisted during the trip by unilateral
braking actions in the vehicle, through which the loading for the
electric servomotor is reduced.
The different method steps are executed and coordinated in a
regulating and/or control unit, which generates actuating signals
for controlling the actuators.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow chart including method steps for switching over,
during braking operation, between an electric drive motor, which is
used in generator mode, and a hydraulic vehicle brake.
FIG. 2 is a timing diagram including the characteristic curve of
different state variables and parameters in the vehicle, while
braking with the aid of the hydraulic vehicle brake and an internal
combustion engine, which is operated in overrun mode by drag
torques.
DETAILED DESCRIPTION
In the flow chart according to FIG. 1, a driving situation in a
vehicle during braking is represented. In method step 1, a driver's
braking request is initially generated, in particular, by
manipulating the brake pedal. In the next method step 2, the
driver's braking request is processed in a regulating and/or
control unit, in which actuating signals are generated for
controlling actuators, by which the braking force to be generated
may be influenced. It is, for example, an electric drive motor 3,
which is operated in generator mode, as well as a hydraulic vehicle
brake 4, which is equipped with an electrically controllable,
hydraulic pump, for example, an ESP pump, for modulating the
hydraulic brake pressure.
In step 2, the braking force to be generated, that is, the braking
torque, is distributed, in the control unit, to electric drive
motor 3 and hydraulic vehicle brake 4. In this context, boundary
conditions may be taken into account both in electric drive motor 3
and in vehicle brake 4; in response to exceedance of limiting
values, the boundary conditions resulting in functional impairment
in the respective actuator.
In the initial state, a selected distribution between electric
drive motor 3 and vehicle brake 4 is carried out. For regeneration,
the vehicle is preferably braked via the generator mode of electric
drive motor 3; vehicle brake 4 only being activated for the case,
in which the requested brake torque may not be supplied exclusively
via the generator mode.
In step 5, the voltage state of the vehicle battery, which is
charged in the generator mode of electric drive motor 3, is
monitored. At a maximum, the generator mode may be sustained until
the battery is completely charged. The current state of charge in
the vehicle battery is monitored; temporally prior to arrival at
the maximum state of charge, which represents a limiting value, a
switchover being made to the vehicle brake as the solely active
actuator during the braking.
In the case of the present invention, the switchover takes place at
a time interval prior to arrival at the maximum state of charge of
the vehicle battery. In this connection, the time interval is
proportionate, inter alia, to the duration of the switchover
operation, which is preferably carried out continuously and
uniformly, by continuously ramping down the braking activity of the
electric drive motor, and at the same time, continuously ramping up
the braking activity of the vehicle brake.
If the inquiry in step 5 reveals that the state of charge of the
vehicle battery has reached a value, which is at a selected time
interval prior to the maximum state of charge, then the Yes-branch
("Y") is returned to control unit 2, in which the switchover
operation between electric drive motor 3 and vehicle brake 4 is
initiated. However, if the inquiry in step 5 reveals that the state
of charge will first be reached in a period of time, which is
longer than the selected time interval, then the No-branch ("N") is
returned again to the start of the inquiry according to step 5, and
this is repeated in cyclical intervals.
In a step 6, the brake temperature, in particular, the brake disk
temperature, may be monitored simultaneously in the vehicle brake.
The brake temperature may not exceed a limiting value. In step 6,
it is checked if the temperature approaches a value, which would
reach the limiting temperature in the event of a further increase
in a selected time interval. If this is not the case, then the
No-branch is returned again to the start of the inquiry according
to step 6, and this is run through repeatedly in cyclical
intervals. However, if the selected time interval prior to arrival
at the critical temperature is reached, then the Yes-branch is
returned to step 2, and in the control unit, a new redistribution
of the braking force to be generated is carried out by switching
over between the actuators.
In principle, the chart shown in FIG. 1 is applicable to different
vehicle control systems, which include at least two actuators, by
which the same driving state variable may be influenced. In this
case, they may be stability systems, for example, anti-roll
stabilization systems in the vehicle, or steering systems.
The characteristic curve of different parameters during downhill
travel of the vehicle, which is in braking operation, is depicted
as a function of time in FIG. 2. Curve s at the top denotes the
downhill travel of the vehicle depicted. The route is predictively
known from data of a navigation system in the vehicle.
The driver inputs a deceleration request a.sub.dr by manipulating
the brake pedal. In the exemplary embodiment, deceleration a.sub.dr
shall be constant.
In a brake pedal switch SW, the braking request produces an
increased, constant value, which reflects the driver's braking
request a.sub.dr, as well as the downhill travel, which is known
from the data of the navigation system.
At time t.sub.0, the vehicle is decelerated both by a braking force
F.sub.br of the hydraulic vehicle brake and, on a lower braking
force level, by a braking force F.sub.ice from an engine drag
torque of the internal combustion engine, which is driven in
overrun mode. This braking action lasts until time t.sub.1.
During the operation of the hydraulic vehicle brake, brake
temperature T.sub.br increases continuously. If the temperature of
the vehicle brake reaches a limiting value T.sub.br,lim, then the
potential function of the vehicle brake P.sub.br falls abruptly to
a value of zero, which means that no more braking force may be
generated by the hydraulic vehicle brake.
Limiting temperature value T.sub.br,lim is reached at time t.sub.2.
By monitoring current brake temperature T.sub.br, time t.sub.1 may
be identified in a selected time interval prior to this, at which
the braking operation is switched over continuously to the internal
combustion engine in overrun mode, in order to generate drag
torques. At time t.sub.1, the brake temperature is not yet in the
critical range.
Accordingly, the time span between t.sub.1 and t.sub.2 for a
continuous transition in the generation of braking force, including
a reduction in braking force F.sub.br of the vehicle brake to a
value of zero and a simultaneous increase in engine drag torque
F.sub.ice to an increased value, is carried out, so that the
desired braking force is attained. This is also valid for the
transition of the hydraulic braking force in the time interval
between t.sub.1 and t.sub.2, in which the hydraulic braking force
is continuously reduced and the engine drag torque is continuously
increased; the requested braking force is also produced during the
transition, from the sum of the hydraulic braking force and engine
drag torque.
As can be deduced from curve P.sub.ice, which indicates the
potential function of the engine drag torque, this remains constant
over the entire time interval considered, which means that the
engine drag torque is available in all of the situations
considered.
* * * * *